Excitation of Skeletal Muscle: Neuromuscular Transmission and Excitation- Contraction Coupling Transmission of Impulses from Nerve Endings to Skeletal Muscle Fibers: The Neuromuscular The skeletal muscle fibers are innervated by large, myelinated nerve fibers that originate from
large motoneurons in the anterior horns of the spinal cord. As pointed out in Chapter 6, each nerve
fiber, after entering the muscle belly, normally branches and stimulates from three to several hundred
skeletal muscle fibers. Each nerve ending makes a junction, called the neuromuscular junction, with
the muscle fiber near its midpoint. The action potential initiated in the muscle fiber by the nerve signal
travels in both directions toward the muscle fiber ends. With the exception of about 2 percent of the
muscle fibers, there is only one such junction per muscle fiber.
